Tracheobronchial implantable medical device and methods of use

ABSTRACT

Devices and methods for treating a diseased tracheobronchial region in a mammal. The device can be a stent which can include a sustained-release material such as a polymer matrix with a treatment agent. The stent can be bioabsorbable and a treatment agent can be incorporated therewith. A treatment method can be delivery of a stent to a tracheobronchial region by a delivery device such as a catheter assembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 11/507,913, filed Aug. 21, 2006, now U.S. Pat. No. 9,173,733,the disclosure of which is incorporated herein by reference.

FIELD OF INVENTION

Bioabsorbable implantable medical devices for the treatment of lesionscaused by cancer of the tracheobronchial tree or cancer of the head,neck or chest.

BACKGROUND OF INVENTION

This invention relates generally to radially expandable endoprostheseswhich are adapted to be implanted in a physiological lumen. An“endoprosthesis” corresponds to an artificial device that is placedinside of a physiological lumen. A “lumen” refers to a cavity of atubular organ such as a blood vessel or other physiological passageway.A stent, or implantable medical device, is an example of anendoprosthesis. Stents are generally cylindrically shaped devices whichfunction to hold open or expand a physiological lumen, or to compress alesion. A stent must be able to satisfy a number of mechanicalrequirements. For example, the stent must be capable of withstanding thestructural loads, namely radial compressive forces, imposed on the stentas it supports the walls of the tubular organ. Accordingly, a stent mustpossess adequate radial strength.

In adults, primary cancer of the tracheobronchial tree or cancer of thehead, neck or chest that extends into the tracheobronchial treefrequently causes lumen compromise and airway obstruction.“Tracheobronchial” refers to the physiological passageway from thethroat to the lungs. In some methods of treatment, a compromisedcomponent of the tracheobronchial tree can be removed by lasertreatment, mechanical debulking, electrocautery, brachytherapy,photodynamic therapy or cryotherapy. A stent can then be placed at thetreatment site following removal of a comprised component to maintainthe airway lumen to counteract collapse or edema.

Alternatively, a stent can be placed to help compress any lesionextending into the tracheo or bronchi without the need for removal ofthe compromised component. In some methods of treatment, a stent hasbeen used to palliate patients with inoperable bronchogenic cancer,primary tracheal tumors and metastatic malignancies.

Stents which have been used in the tracheobronchial tree include metal,silicone and bioabsorbable stents. Metallic stents are generally madefrom an inert metal such as stainless steel, cobalt chromium andNitinol. Some problems associated with known stent types delivered tothe tracheobronchial region include inflammation, stent migration,epithelial damage, granulation tissue formation and mucous plugging. Inaddition, it is believed that known bioabsorbable stents designed forplacement in the tracheobronchial region are not able to adequatelycombat inflammation caused by stent placement.

“Stent migration” refers to the gradual movement of the stent down thetracheobronchial tree after placement thereof. Stent migration ofsilicone stents in the tracheobronchial tree is common. “Mucousplugging” is an excessive production of mucous produced in response tothe stent. Mucous plugging can cause interference with breathing.“Granulation tissue formation” is the formation of new tissue inresponse to a wound or other disruption of tissue. Excessive granulationtissue formation can cause a stent to be permanently lodged within apassageway complicating removal if required. Metal stents are especiallysusceptible to granulation tissue formation. Accordingly, atracheobronchial stent which addresses these problems is desirable.

SUMMARY OF INVENTION

Devices and methods for treating a diseased tracheobronchial region in amammal are herein disclosed. The device can be a stent which can includea sustained-release material such as a polymer matrix with a treatmentagent. The stent can be a bioabsorbable stent and a treatment agent canbe incorporated therewith. A treatment method can be delivery of a stentto a tracheobronchial region by a delivery device such as a catheterassembly.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a side view of an embodiment of a stent of thepresent invention.

FIG. 2 illustrates a side view of an alternative embodiment of a stentof the present invention.

FIG. 3A illustrates side view of a first alternative embodiment of astent of the present invention.

FIG. 3B illustrates side view of a second alternative embodiment of astent of the present invention.

FIG. 3C illustrates an embodiment of a braided stent with variableradial strength.

FIG. 3D illustrates an embodiment of a coiled stent with variable radialstrength.

FIG. 4A illustrates an elevational view, partially in section, of adelivery system having a covered stent on a catheter balloon which maybe used pursuant to methods of the present invention.

FIG. 4B is a cross-section of the delivery system of FIG. 4A taken atline 2-2.

FIG. 4C is a cross-section of the delivery system of FIG. 4B taken atline 3-3.

DETAILED DESCRIPTION

Embodiments of devices and methods for treating a diseasedtracheobronchial region in a mammal, including, but not limited to,humans, are herein disclosed. In some embodiments, the device can be animplantable medical device such as a stent. Representative examples ofimplantable medical devices include, but are not limited to,self-expandable stents, balloon-expandable stents, micro-depot ormicro-channel stents and grafts. In some embodiments, a treatment methodcan be delivery of a stent to a tracheobronchial region by a deliverydevice such as a catheter assembly.

In some treatment applications, a stent may only be required to bepresent in the tracheobronchial region for a limited period of time. Toaccommodate this, a stent can be made of a biodegradable, bioerodable orbioabsorbable polymer, hereinafter used interchangeably. A stent canalso be made of a biostable or biodurable (hereinafter usedinterchangeably) or a combination of a biostable and biodegradablepolymer. A stent made from a biodegradable polymer is intended to remainin the body for a duration of time until its intended function of, forexample, maintaining luminal patency and/or drug delivery, isaccomplished. After the process of degradation, erosion, absorptionand/or resorption has been completed, none or substantially none of thebiodegradable portion of the stent will remain in the tracheobronchialregion.

In some embodiments, the stent may include a treatment agent. As usedherein, treatment agents are intended to include, but are not intendedto be limited to, drugs, biologically active agents, chemically activeagents, therapeutic agents, and the like, and pharmaceuticalcompositions thereof, which can be used to deliver a treatment agent toa treatment site as described herein. Representative treatment agentsinclude, but are not limited to, an anti-inflammatory, an anti-platelet,an anti-coagulant, a fibrinolytic, an anti-thrombonic, an anti-mitotic,an anti-biotic, an anti-allergic, an anti-oxidant, an anti-proliferativeand an anti-migratory. The treatment agent may be incorporated withinthe body of the stent or within a polymer-based coating applied on orwithin the stent.

Tracheobronchial Stents

FIG. 1 illustrates an embodiment of a stent. Stent 100 is generallytubular and includes a lumen 102 with an abluminal surface 104 and aluminal surface 106. Stent 100 can include a plurality of struts 108connected by linking struts 110 with interstitial spaces 112 locatedtherebetween. The plurality of struts 108 can be configured in anannular fashion in discrete “rows” such that they form a series of“rings” throughout the body of stent 100. Thus, stent 100 can include aproximal ring 114, i.e., proximal concentric end region, distal ring116, i.e., distal concentric end region, and at least one central ring118, i.e., middle concentric region. In some embodiments, proximal ring114 and distal ring 116 can have a larger outer diameter than that ofcentral rings 118. For example, the outer diameter (OD) of central rings118 can be from about 3.5 mm to about 25 mm, and in some embodiments,from about 8 to about 20 mm. The OD of proximal ring 114 and distal ring116 can be from about 5.0 mm to about 30 mm, and in some embodiments,from about 10 to about 22 mm. Such configuration may reduce or eliminatestent migration.

FIG. 2 illustrates an alternative embodiment of a stent. Stent 200 isgenerally tubular and includes a lumen 202 with an abluminal surface 204and a luminal surface 206. Stent 200 can include a series of filaments208 which can be interconnected in a braided, twisted or coiled fashion.Filaments 208 may be fabricated from a biodurable or biodegradable metalor polymer. Tubular stent 200 can include a proximal end 214, a distalend 216 and at least one central portion 218. In some embodiments,proximal end 214 and distal end 216 can have a larger outer diameterthan that of central portion 218 similar to those ranges given withrespect to FIG. 1. Stent 200 can be a self-expanding stent.

FIG. 3A illustrates another alternative embodiment of a stent. Stent 300is generally tubular and includes a lumen 302 with an abluminal surface304 and a luminal surface 306. Stent 300 can include a series offilaments 308 which can be interconnected in a braided, twisted, weavedor coiled fashion. Filaments 308 may be fabricated from a biodurable orbiodegradable metal or polymer. Tubular stent 300 can include a proximalend 314, a distal end 316 and at least one central portion 318. In someembodiments, proximal end 314 and distal end 316 can have a larger outerdiameter than that of central portion 318 similar to those ranges givenwith respect to FIG. 1. Stent 300 can be a self-expanding stent.

FIG. 3B illustrates another alternative embodiment of a stent. Stent 301is generally tubular and includes a lumen 303 with an abluminal surface305 and a luminal surface 307. Stent 301 can include a series offilaments 309 which can be interconnected in a braided, twisted, weavedor coiled. Filaments 309 may be fabricated from a biodurable orbiodegradable metal or polymer. Tubular stent 301 can include a proximalend 315, a distal end 317 and at least one central portion 319 similarto those ranges given with respect to FIG. 1. In some embodiments,proximal end 315 and distal end 317 can have a larger outer diameterthan that of central portion 319. Stent 301 can be a self-expandingstent.

In some embodiments, a stent according to the present invention can havevariable radial strength along the stent length. For example, the stentcan have higher radial strength at the proximal and distal ends relativeto the central portions. In this aspect, the higher radial strengthproximal and distal ends can serve as “anchors” after placement in thetracheobronchial tree. It is anticipated that higher radial strengthproximal and distal ends can substantially minimize, or even prevent,stent migration.

FIG. 3C illustrates an embodiment of a braided stent with variableradial strength. Stent 320 includes proximal end 322, distal end 324 andat least one central portion 326. Proximal end 322 and distal end 324can have higher picks per inch, or pitch (hereinafter referred tointerchangeably), which can give ends 322 and 324 higher radial strengthrelative to central portion 326. “Pitch” is the density of material in agiven unit of length. In some embodiments, a thin polymer fiber can beextruded, drawn and heat set to the dimensions ranging from about 0.003inches to about 0.010 inches. The fibers can be wound onto a bobbin orspool and braided into a stent using a braiding machine. Braidingmachines for stent fabrication are generally known by those skilled inthe art. The pitch for central portion 326 of stent 320 can bepredetermined by using the appropriate gear dimension in the braidingmachine in the braiding machine to produce a predetermined picks perinch. Once central portion of stent 320 has been braided, the geardimension in the braiding machine can be changed to accommodatefabrication of higher picks per inch of proximal end 322 and distal end324. In some embodiments, central portion 326 can have a pitch of about40 to about 90 picks per inch while ends 322 and 324 can have a pitchfrom about 60 to about 100 picks per inch. In any case, the proximal anddistal ends will have higher picks per inch as compared to the centralportion. In some embodiments, ends 322 and 324 can be from about 1.0 mmto about 5.0 mm. After braiding, stent 320 can be heat set. For example,in braided stents comprised of poly-L-lactic acid, heat setting can bedone at between about 120° C. to about 160° C. for about 10 to about 30minutes.

FIG. 3D illustrates an embodiment of a coiled stent with variable radialstrength. Stent 321 includes proximal end 323, distal end 325 and atleast one central portion 327. Proximal end 323 and distal end 325 canhave a higher pitch angle, which can give ends 323 and 325 higher radialstrength relative to central portion 327. “Pitch angle” is defined asthe angle between the direction of the fiber and longitudinal axis. Insome embodiments, a thin polymer fiber can be extruded, drawn and heatset to the dimensions ranging from about 0.003 inches to about 0.010inches. The fiber can be coiled onto a mandrel with a predeterminedpitch angle for central portion 327. Proximal end 323 and distal end 325can be constructed using a higher pitch angle to increase radialstrength. In some embodiments, central portion 327 can have a pitchangle of about 25° to about 70°, while ends 323 and 325 can have a pitchangle from about 50° to about 90°. In any case, the pitch angle at theproximal and distal ends will be higher than the central portion forincreased radial strength. In some embodiments, ends 323 and 325 can befrom about 1.0 mm to about 10.0 mm. After coiling, stent 321 can be heatset. For example, in coiled stents comprised of poly-L-lactic acid, heatsetting can be done at between about 120° C. to about 160° C. for about10 to about 30 minutes.

In general, a stent is designed so that the stent can be radiallycompressed (crimped) and radially expanded (to allow deployment). Thestresses involved during compression and expansion are generallydistributed throughout various structural elements of the stent. As astent deforms, various portions of the stent can deform to accomplishradial expansion. In this aspect, the stent must be sufficientlymalleable to withstand compression and expansion.

On the other hand, the stent must exhibit a certain degree of rigidityto maintain lumen patency during its lifetime. For a bioabsorbablestent, a lifetime can be from about 2 months to about 24 monthsdepending on the intended application. Thus, a biodegradable stent ispreferably fabricated from a polymer which allows for sufficientmalleability during compression and expansion, and sufficient rigidityafter deployment thereof.

Representative examples of polymers that may be used to manufacture orcoat a stent, include but are not limited to, poly(N-acetylglucosamine)(Chitin), Chitosan, poly(hydroxyvalerate), poly(lactide-co-glycolide),poly(hydroxybutyrate), poly(hydroxybutyrate-co-valerate),polyorthoester, polyanhydride, poly(glycolic acid), poly(glycolide),poly(L-lactic acid), poly(L-lactide), poly(D,L-lactic),poly(caprolactone), poly(trimethylene carbonate), polyester amide,poly(glycolic acid-co-trimethylene carbonate), co-poly(ether-esters)(e.g. PEO/PLA), polyphosphazenes, biomolecules (such as fibrin,fibrinogen, cellulose, starch, collagen and hyaluronic acid),polyurethanes, silicones, polyesters, polyolefins, polyisobutylene andethylene-alphaolefin copolymers, acrylic polymers and copolymers otherthan polyacrylates, vinyl halide polymers and copolymers (such aspolyvinyl chloride), polyvinyl ethers (such as polyvinyl methyl ether),polyvinylidene halides (such as polyvinylidene chloride),polyacrylonitrile, polyvinyl ketones, polyvinyl aromatics (such aspolystyrene), polyvinyl esters (such as polyvinyl acetate),acrylonitrile styrene copolymers, ABS resins, polyamides (such as Nylon66 and polycaprolactam), polycarbonates, polyoxymethylenes, polyimides,polyethers, polyurethanes, rayon, rayon-tracetate, cellulose, celluloseacetate, cellulose butyrate, cellulose acetate butyrate, cellophane,cellulose nitrate, cellulose propionate, cellulose ethers, andcarboxymethyl cellulose. Another type of polymer based on poly(lacticacid) that can be used includes graft copolymers, and block copolymers,such as AB block-copolymers (“diblock-copolymers”) or ABAblock-copolymers (“triblock-copolymers”), or mixtures thereof.

Additional representative examples of polymers that may be especiallywell suited for use in manufacturing or coating stents include ethylenevinyl alcohol copolymer (e.g., EVOH or EVAL), poly(butyl methacrylate),poly(vinylidene fluoride-co-hexfluorapropene (e.g., SOLEF 21508,available from Solvay Solexis PVDF, Thorofare, N.J.), polyvinylidenefluoride (e.g., KYNAR, available from ATOFINA Chemicals, Philadelphia,Pa.), ethylene-vinyl acetate copolymers and polyethylene glycol.

Manufacturing processes for forming a bioabsorbable stent include, butare not limited to, casting, molding, extrusion, drawing or combinationsthereof. Casting involves pouring a liquid polymeric composition into amold. Molding processes include, but are not limited to, compressionmolding, extrusion molding, injection molding and foam molding. Incompressing molding, solid polymeric materials are added to a mold andpressure and heat are applied until the polymeric material conforms tothe mold. In extrusion molding, solid polymeric materials are added to acontinuous melt that is forced through a die and cooled to a solid form.In injection molding, solid polymeric materials are added to a heatedcylinder, softened and forced into a mold under pressure to create asolid form. In foam molding, blowing agents are used to expand and moldsolid polymeric materials into a desired form, and the solid polymericmaterials can be expanded to a volume in a range from about 2 to about50 times their original volume. In the above-described moldingembodiments, the solid form may require additional processing to obtainthe final product in a desired form. Additional processing may includefiber processing methods such as hot drawing to induce orientation andhigher crystallinity for increased mechanical strength.

The material for the stent can also be produced from known man-madefiber processing methods such as dry spinning, wet spinning, and meltspinning. In dry spinning, a polymer solution in warm solvent is forcedthrough a tiny hole into warm air. The solvent evaporates into the airand the liquid stream solidifies into a continuous filament. Wetspinning method involves a polymer solution forced through tiny holesinto another solution where it is coagulated into a continuous filament.Melt spinning method is a method in which a solid polymer is melted andforced through a tiny hole into cool air which solidifies the fiber intoa continuous filament.

In some embodiments, a stent may be fabricated from a biocompatiblemetal or metal alloy. Representative examples include, but are notlimited to, stainless steel (316L or 300), MP35N, MP2ON, Nitinol,Egiloy, tantalum, tantalum alloy, cobalt-chromium alloy, nickel-titaniumalloy, platinum, iridium, platinum-iridium alloy, gold, magnesium orcombinations thereof. MP35N and MP2ON are trade names for alloys ofcobalt, nickel, chromium and molybdenum available from Standard PressSteel Co., Jenkintown, Pa. MP35N consists of 35 percent (%), cobalt, 35%nickel, 20% chromium and 10% molybdenum. MP2ON consists of 50% cobalt,20% nickel, 20% chromium and 10% molybdenum.

In some embodiments, a treatment agent may be directly incorporated intothe body of a bioabsorbable stent during the manufacturing process. Forexample, a treatment agent may be combined with a polymer matrix andsubsequently subjected to any of the above-described manufacturingprocess for formation thereof. In this aspect, the treatment agent maybe released in a controlled manner as the bioabsorbable stent naturallydegrades in the tracheobronchial region.

In some applications, a polymer coating comprising at least one layerincluding a treatment agent can be applied to a surface of a stent forcontrolled release of the treatment agent. The polymer can be a polymerwhich exhibits a sustained-release characteristic of the treatmentagent. For example, the polymer can be polyglycolide (PGA) which has adegradation rate of about 9 months to about 12 months. In anotherexample, the polymer can be polylactide (PLA) which has a degradationrate of about 14 and about 18 months. Copolymers of PLA and PGA can alsobe used to tailor degradation rates. It should be appreciated that morethan one coating may be applied to treat a variety of symptoms typicallyexperienced with tracheobronchial stent placement.

For example, a coating can include one or a combination of the followingtypes of layers: (a) a treatment agent layer, which may include apolymer and a treatment agent, or alternatively, a polymer-freetreatment agent; (b) an optional primer layer, which may improveadhesion of subsequent layers on the stent or on a previously formedlayer; (c) an optional topcoat layer, which may serve to control therate of release of the treatment agent; and (d) an optionalbiocompatible finishing layer, which may improve the biocompatibility ofthe coating.

In some embodiments, the coating can be partially or completely appliedto an abluminal surface or a luminal surface of the stent. The coatingcan be applied by methods known by those skilled in the art, including,but not limited to, dipping, spraying, pouring, brushing, spin-coating,roller coating, meniscus coating, powder coating, drop-on-demandcoating, sputtering, gas-phase polymerization, solvent inversion or anycombination thereof. Coating techniques are known by those skilled inthe art.

The coating which includes a treatment agent can include, but is notlimited to, an anti-inflammatory, an anti-platelet, an anti-coagulant, afibrinolytic, an anti-thrombonic, an anti-mitotic, an anti-biotic, ananti-allergic, an anti-oxidant, an anti-proliferative and ananti-migratory. In some embodiments, the treatment agent can be ananti-inflammatory steroid or non-steroid. Examples of anti-inflammatorysteroids include, but are not limited to, prednisone, oxymetholone,oxandrolone and methanodrostenolone. Examples of anti-inflammatorynon-steroids (NSAID) include, but are not limited to, ibuprofen,diclofenac, diflunisal, fenoprofen, aspirin, sulindac, naproxen,indomethacin, piroxicam, ketoprofen, tolmetin and azapropazonelast.

The treatment agent can treat symptoms typically associated withtracheobronchial stent deployment, such as, inflammation, epithelialdamage, granulation tissue formation and mucous plugging.

Methods of Delivery

FIGS. 4A-4C illustrate an over-the-wire type stent delivery ballooncatheter 400 which can be used pursuant to embodiments of the presentinvention. Catheter 400 generally comprises an elongated catheter shaft402 having an outer tubular member 404 and an inner tubular member 406.Inner tubular member 406 defines a guidewire lumen 408 adapted toslidingly receive a guidewire 410. The coaxial relationship betweenouter tubular member 404 and inner tubular member 406 defines annularinflation lumen 412 (see FIGS. 4B and 4C, illustrating transverse crosssections of the catheter 400 of FIG. 4A, taken along lines 2-2 and 3-3respectively). An inflatable balloon 414 is disposed on a distal sectionof catheter shaft 402, having a proximal shaft section sealingly securedto the distal end of outer tubular member 404 and a distal shaft sectionsealingly secured to the distal end of inner tubular member 406, so thatits interior is in fluid communication with inflation lumen 412. Anadapter 416 at the proximal end of catheter shaft 402 is configured todirect inflation fluid through arm 418 into inflation lumen 412 and toprovide access to guidewire lumen 408. Balloon 414 has an inflatableworking length located between tapered sections of the balloon, with anexpandable stent 420 mounted on the balloon working length. FIG. 4Aillustrates the balloon 414 in an uninflated configuration prior todeployment of the stent 420. The distal end of catheter may be advancedto a desired region of a patient's body lumen 422 in a conventionalmanner, and balloon 414 inflated to expand stent 420, seating the stentin the body lumen 422. A stent cover 430 is on an outer surface of thestent 420. Stent cover 430 generally comprises a tubular body, whichpreferably conforms to a surface of the stent and expands with the stentduring implantation thereof in the patient. Although stent cover 430 isillustrated on an outer surface of the stent 430 in FIG. 4A, the stentcover may be provided on all or part of an inner and/or an outer surfaceof the stent 420.

It should be appreciated that, in some embodiments, a self-expandingstent may be delivered by a stent delivery catheter without (or with) aballoon. Various methods are employed for delivery and implantation of aself-expanding stent. For instance, a self-expanding stent may bepositioned at the distal end of a catheter around a core lumen.Self-expanding stents are typically held in an unexpanded state duringdelivery using a variety of methods including sheaths or sleeves whichcover all or a portion of the stent. When the stent is in its desiredlocation of the targeted vessel the sheath or sleeve is retracted toexpose the stent which then self-expands upon retraction.

In some methods, a stent according to the present invention may bedelivered to a tracheobronchial region by a stent delivery catheter(with or without a balloon) for treatment thereof.

From the foregoing detailed description, it will be evident that thereare a number of changes, adaptations and modifications of the presentinvention which come within the province of those skilled in the part.The scope of the invention includes any combination of the elements fromthe different species and embodiments disclosed herein, as well assubassemblies, assemblies and methods thereof. However, it is intendedthat all such variations not departing from the spirit of the inventionbe considered as within the scope thereof.

What is claimed is:
 1. A method comprising: delivering a bioabsorbablestent to a tracheobronchial region of a mammal, wherein a treatmentagent is disposed on or within at least a portion of the stent, and thetreatment agent (a) is subjected to controlled release and (b) treats atleast one of granulation tissue formation, mucous plugging andinflammation; and positioning the stent in the tracheobronchial regionby self-expanding the stent within a trachea or a bronchi of the mammaland anchoring a proximal end and a distal end of the stent to a wall ofthe trachea or the bronchi to prevent stent migration, wherein theproximal end and the distal end of the stent have a pitch of from 60 to100 picks per inch, and the pitch of the proximal end and the distal endis greater than a pitch of a central portion of the stent such that aradial strength at the proximal end and the distal end is greater thanthe central portion and anchors the stent to the wall of the trachea orthe bronchi.
 2. The method of claim 1 wherein the treatment agent iscombined with a polymer matrix forming a mixture and the mixture iscoated on at least one of an abluminal or a luminal surface of thestent.
 3. The method of claim 2 wherein the polymer matrix is selectedfrom the group consisting of polyglycolide, polylactide, and copolymersand combinations thereof.
 4. The method of claim 1 wherein the treatmentagent is incorporated within the body of the stent.
 5. The method ofclaim 1 wherein the bioabsorbable stent comprises a material selectedfrom the group consisting of polylactide, polyglycolide,polycaprolactones, and copolymers and combinations thereof.
 6. Themethod of claim 1 wherein the treatment agent is an anti-inflammatory.7. The method of claim 6 wherein the anti-inflammatory is selected fromthe group consisting of prednisone, oxymetholone, oxandrolone,methanodrostenolone, ibuprofen, diclofenac, diflunisal, fenoprofen,aspirin, sulindac, naproxen, indomethacin, piroxicam, ketoprofen,tolmetin and azapropazonelast.
 8. The method of claim 1 wherein thecontrolled release is from about 2 to about 24 months.
 9. The method ofclaim 1 wherein the stent comprises a cylindrical body, wherein an outerdiameter of the proximal end and an outer diameter of the distal end aregreater than an outer diameter of the central portion.
 10. The method ofclaim 1 wherein the stent comprises a cylindrical body, wherein theproximal end and the distal end have a greater pitch angle than thecentral portion.
 11. The method of claim 10 wherein the central portionhas a pitch of between 40 to 90 picks per inch.
 12. The method of claim10 wherein the proximal end and the distal end have a pitch angle ofbetween 50 degrees and 90 degrees and the central portion has a pitch ofangle of about 25 degrees to about 70 degrees.
 13. The method of claim 1wherein the treatment agent is part of a multi-layer coating disposed onat least a portion of the stent, and wherein the multi-layer coatingcomprises (i) a treatment layer comprising the treatment agent, (ii) aprimer layer for improving adhesion of an adjacent layer, and (iii) abiocompatible finishing layer for improving a biocompatibility of themulti-layer coating.
 14. A method comprising: delivering a bioabsorbablestent to a tracheobronchial region of a mammal, wherein a treatmentagent is disposed on or within at least a portion of the stent, and thetreatment agent (a) is subjected to controlled release and (b) treats atleast one of granulation tissue formation, mucous plugging andinflammation; and positioning the stent in the tracheobronchial regionby self-expanding the stent within a trachea or a bronchi of the mammal,and wherein the stent comprises a proximal concentric end region, amiddle concentric region and a distal concentric end region, and a pitchof the proximal concentric end region and the distal concentric endregion is greater than a pitch of the middle concentric region such thata radial strength at the proximal concentric end region and the distalconcentric end region is greater than the middle concentric region andanchors the stent to the wall of the trachea or the bronchi, and thepitch of the middle concentric region is between 40 to 90 picks perinch.
 15. The method of claim 14 wherein the bioabsorbable stent isself-expanding.
 16. The method of claim 14 wherein the proximalconcentric end region and the distal concentric end region have a pitchof between 60 to 100 picks per inch.
 17. The method of claim 14 whereinthe proximal concentric end region and the distal concentric end regionhave an outer diameter of from about 5 mm to about 25 mm.
 18. The methodof claim 14 wherein the proximal concentric end region and the distalconcentric end region have an outer diameter of from about 5 mm to about25 mm, and an outer diameter of the middle concentric region is lessthan the outer diameter of the proximal concentric end region and thedistal concentric end region.
 19. The method of claim 14 wherein themiddle concentric region comprises an outer diameter of from about 3.5mm to about 25 mm.